Response to bronchodilation with tiotropium plus salbutamol correlates with radiologic morphology of the lung in COPD of the emphysematous phenotype

Aim of this study was to assess relationships between response to bronchodilation with tiotropium plus salbutamol and computed-tomography-based emphysema severity measures in patients with COPD of the emphysematous phenotype. Forty-four consecutive patients (38 males and 6 females) who met inclusion criteria for lung volume reduction, were included in a prospective nonrandomized study. Following in-hospital 48h-washout from all bronchodilators, spirometry and plethysmography were performed before and after administration of tiotropium (18µg) and salbutamol (200µg). Morphology of emphysema measures including degrees of severity (ES)(possible scores:12-48) and heterogeneity (HT)(possible scores:0-3) were graded on thin section high-resolution computed tomography slices by a previously validated visual scoring system. Mean age was 638.4 years. Scores in ES and HT were 315 and 1.250.6, respectively. Pre-bronchodilator values of FEV1, FVC and plethysmographic residual volume (RVplet) were 1.280.58L (3718% predicted), 2.610.78L (6616% predicted) and 5.221.1L (22058% predicted), respectively. Post-bronchodilators change in FEV1, FVC and RVplet were 0.170.1L (+17%) , 0.540.3L (+24%) and 0.820.4L (-15%), respectively. A direct correlation was found between FVC and HT (R=0.31, P=0.03) and between RVplet and ES (R=0.50, P=0.0004). Our study results have shown that in patients with COPD of the emphysematous phenotype, significant post-bronchodilation changes in lung volumes correlated with computed tomography-based emphysema severity measures. We speculate that airway-to-parenchyma interdependence modulate response to bronchodilators in these patients.